Telephone system



E. H. CLARK TELEPHONE SYSTEM Filed Sept. 18, 1923 Dec. 1 1925. 1,563,556

Patented Dec. 1, 1925.

UNITED STATES PATENT OFFlflE EDGAR H. CLARK, OF RICHMOND HILL, NEW YORK,ASSIG-NOR TO WESTERN ELEC- TRIO COMPANY, INCORPORATED, OF NEW YORK, N.Y., A CORPORATION OF NEW YORK.

TELEPHONE SYSTEM.

Application filed September 18, 1923.

T 0 all whom it may coaccwi:

Be it known that I, Enean H. CLARK, a citizen of the United States ofAmerica, residing at Richmond Hill, in the countyof Queens and State ofNew York, have invented certain new and useful Improvements in TelephoneSystems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone systems and particularly to machineswitching systems in which coordinate type switching mechanism isemployed.

The object of the invention is to produce a controlling arrangementwhich will be positive and accurate in its action.

A feature of the invention resides in the use of slow acting relays, theoperation of which depends in such a manner upon the voltage that theoperating time interval may be held substantially constant for varyingvoltages, such variations as may occur being of a desirable character.

I-Ieretofore in circuit arrangements such as shown in the patent to S.B. WVilliams, No. 1,517,331, granted December 2, 1924, where it isnecessary to cause a heavy current to flow to produce a certainresult'such as to operate a magnet and to thereafter reduce the flow ofsuch current, timing means such as a slow-releasing relay is dependedupon to measure the interval. Due to the fact that a slow-releasingrelay is energized for a comparatively long period prior to the openingof its circuit, its core has had time to become fully saturated, thedegree of saturation depending directly upon the voltage. To-insure thatthe releasing time of the relay shall always be at least equal to arequired minimum, it is necessary to saturate the relay to a degreerepresented by a point out on the flat part of the well knownmagnetization curve. On this portion of the curve, a given increase involtage corresponds to a much greater time increment in the release ofthe relay than on the steep portion of the curve. Hence, for increasingvoltages the time interval during which the heavy current flows ismaterially increased to the possible detriment of the apparatus.

In the present arrangement this diliiculty is overcome by the use ofslow-to-operate rc lays. The operating interval of these relays is moreindependent of voltage changes due to the fact that their magnetizationbegins Serial No. 663,333.

at practically zero and is represented by the steep portion of thecurve. It may be seen from the description of the circuits hereinafterthat since the interval is measured by the operating time of a relay andnot by the releasing time, if an increment of increase in voltage causesthe timing relay to operate slightly faster, this fact will beadvantageous. This is a desirable result since the increased voltagecauses a quicker operation of the heavy current magnets and thereforethe time interval to provide for the completion of the operation of themagnet may be correspondingly short.

The invention is shown in a single sheet of drawing comprising adiagrammatic illustration of the preferred form of circuit arrangement.

When the subscriber at substation 1 removes his receiver from its hook,line relay 2 becomes energized. Relay 4 thereupon operates over acircuit from ground, back contact and inner lefthand armature of relay3, front contact and righthand armature of line relay 2, winding ofrelay 4 to grounded battery. Relay 4 causes the energization of relay 3through its inner right-hand armature and closes a circuit from ground,normal contacts of the armature of relay 5, armature and back contact ofrelay 6, outer right-hand armature of relay 4:, right-hand winding ofrelay 7 to battery and-ground. Relay 7 attracts its armatures andcloses, first a circuit for relay 8 through its outer righthandarmature, second, a holding circuit for relay 3 through its innerright-hand armature, and third, a locking circuit for itself fromground, normal contacts of the armature of relay 5, winding of relay 6,inner left-hand armature and back contact of relay 9, inner left-handarmature and front contact of relay 7, left-hand winding of re lay 7 tobattery and ground. The energization of relay 3 opens the circuit ofrelay 4 so that this relay now becomes deenergized but relays 3, 7 and 8remainenergized. In series with relay 7, relay 6 becomes energized andtransfers the ground connection from its back contact to its frontcontact whereupon a circuit is established from ground, the normalcontacts of the armature of relay 5, armature and front contact of relay6, left-hand armature and back contact of relay l0, outer left-handarmature and front contact of relay 7 outer left-hand armature and frontcontact of relay 3, lefthand armature and front contact of relay 2,upper winding of relay 11 to battery and ground. Relay 11 becomesenergized in this circuit and closes a locking circuit through thewinding of relay 10, the inner lower armature and front contact of relay11, the lower winding of relay 11 to battery and ground. Relay 10operates in this circuit. Ground is now extended from the armature andfront contact of relay 10 through the upper armature and front contactof relay 11 to vertical magnet 12 causing the energization of thismagnet. At the same time, a circuit is closed from ground, theari'nature and front contact of relay 10, through the lowermost armatureand front contact of relay 11, the inner lower arn'iature and backcontact of relay l3, winding of vertical magnet lt to battery and groundcausing the energization of this magnet. Upon the energiZation ofmagnets 1.2 and 14: a circuit is closed from ground, front contact andouter lower armature of magnet 1e, conductor 15, outer lower arn'iatureand front contact of magnet 12, conductor 16, winding of relay 17 tobattery and ground. Simultaneously therewith a circuit is closed fromground through the front contact and outer lower armature of magnet ll,conductor 15, theinner lower armature and front contact of magnet 12,conductor 18. front contact and innermost left-hand armature of relay 8,inner left-hand armature and back contact of relay 19, right-handwinding of horizontal magnet 20 to battery and ground, It will be notedthat the two vertical magnets ointly control the circuit for theenergization of the horizontal magnet and that at the same time theyclose a circuit for limiting the energization of the horizontal magnet.This circuit is through the winding of relay 1? as traced. Upon theclosure of this circuitthe armature of relay 1? is attracted but thisrelay being slow to operate does not close the circuit controlled byitself for a definite interval. At the end of this interval, relay whichis also a slow operating relay becomes energized. Thus, through theoperation of relays 17 and 5, the ground supplied at the normal contactsof the armature of relay is removed in a definite interval which ismeasured from the time when magnet 20 first becomes operated.

Upon the energization of magnets 12, 1t and 20, switching devices 21 and22 become operated so that the line of substation 1 is extended to trunkUpon the establishment of this connection, a ground is extended over thefront contact and inner lower armature of magnet 14k to the thirdconductor of the line which leads to the cut-off rela -f 24 which,becoming energized, opens the circuit for line relay 2. This groundconnection to the third conductor through the ucasse agency of magnet14; is only temporary and will remain there only until the ground isreturned on the third conductor from the apparatus connected to trun t23 in the ordinary and well known manner.

Upon the energization of relay .1, relays (i' and become deenergizedwhereupon the magnets 12 and let. immediately restore their armaturesand by so doing remove the. ground supplied for the energization ofmagnet 20. However, by this time a ground is extended over the thirdconductor of the transfer circuit leading between switching devices 21and 22 through the winding of relay 19 and thence through the twowindings of magnet in series, which is sufficient not only to energizerelay 19 but to cause the continued energization of magnet 20. Theenergization of relay 5 also causes the deenergization of relays 3, 7and 8 which release. The locking circuit of relay 11 is also opened andthis relay becomes deenergized but relay 13 becomes energized upon thedeenergization of magnet 14 in a circuit from the third conductor of thetrunk through the inner lower armature of magnet 14 at its back contactand the upper winding of relay 13 to battery and ground.

The lower winding of relay 13 is provided so that if during theextension of a connection to another trunk, the circuit for the up perwinding of relay 13 should become opened then this relay will remainenergized through its lower winding and hence in this way doubleconnections are prevented.

At the end of the conversation the ground on the third conductor oftrunk 23 is removed in the well known manner resulting in thedeenergization of relays 13, 19 and 2a and the deenergization of magnet20 whereupon the apparatus concerned in this connection is whollyrestored to normal.

lVhat is claimed is: I

1. In a telephone system, line magnets, link magnets, trunk magnets, acircuit for said link magnets controlled by said other magnets, and timecontrolling means for limiting the closing period of said circuit to adefinite interval.

2. In a telephone system, line magnets, link magnets, trunk magnets, acircuit for said link magnets controlled by said other magnets-andanother circuit controlled by said other magnets including relays slowto operate, said slow operating relays determining the closing period ofsaid first circuit.

in a telephone system, lines, links and trunks, separately operableswitching mechanisms for connecting said lines to said links, separatelyoperable switching mechanisms for connecting said links to said trunks,line magnets, link magnets and trunk magnets cooperating to operate saidswitching mechanisms to extend said lines through said links to saidtrunks, circuits for said link magnets controlled by said other magnets,and timing means for determining the length of the closing period ofsaid circuit.

4:. In a coordinate telephone system, line and trunk magnets forpreparing a connection, link magnets for completing a preparedconnection, circuits for said link magnets controlled by said othermagnets, a timing device, and a circuit for said device controlled bysaid other magnets, said device having means for limiting the controlexercised over said link magnets to a definite interval.

5. The combination in a telephone system of a switch having a link forinterconnecting incoming and outgoing lines, a magnet for said link,switch operating members, a circuit for said magnet, a timing relay, acircuit for said relay, both said circuits being closed by said switchoperating members, means controlled by said relay upon its operation foropening the circuit of said magnet, and a source of energy for operating both the relay and the magnet, said relay adapted to measure aninterval always greater than the interval required for the magnet tooperate.

In witness whereof, I hereunto subscribe my name this 4th day ofSeptember A. D, 1923.

EDGAR H. CLARK.

